Energy policy has been under review on every level such as municipalities, corporations, and civilians in the viewpoint of preventing global warming.
In the field of electric energy, it has been proposed to eliminate the loss in electric power transmission and to raise energy efficiency by effectively utilizing waste heat by shifting from a large scale, which is centralized power plant system to a small scale electric power source dispersed in the region.
On the other hand, there are energy-saving technologies conducted by corporations such as co-generation and regional air conditioning. Further, recently, distributed small co-generation apparatuses such as micro gas turbines, fuel cells which are usable at the popular level such as housing complex and convenience stores are under development, which operate on town gas or natural gas.
Effort to improve the efficiency of these small apparatuses themselves is being continued, however, it is more than ever necessary to raise total energy efficiency as a whole region, that is, zero emission of heat is demanded.
For this reason, there has been developed several technologies to utilize the waste heat discharged from distributed air conditioning apparatuses for absorption or adsorption refrigerating machines after adjusting the temperature of the waste heat by heat-exchange with soil and the like to raise the coefficient of performance of individual air conditioning apparatus for raising energy efficiency as a whole district.
However, in most cases the excess in heat source systems is dissipated into the atmosphere in prior arts.
The excess heat in heat source systems used on citizen level such as distributed small scale co-generation apparatuses is difficult to be utilized, so the excess heat is discarded without utilized if there is no system for recovering and reusing the excess heat, and this promotes heat island phenomenon.
Heat emission from small apparatuses distributed over shopping districts or housing complex may increase, which is not assumed in the past, and it is demanded to effectively utilize the waste heat.
In the light of the problem mentioned above, there was a regional air conditioning system as a heat supplying system through regional piping. In the beginning, a 4-pipe method was adopted to supply hot water and cold water of temperatures demanded through exclusive going and returning pipes. Heat insulation of the pipes was necessary and effective utilization of the returning pipes was a problem.
As an improvement of the 4-pipe method was proposed a 2-pipe method in which each pipe is used for supplying or returning alternately according to seasons or time periods.
In Japanese Patent Publication No.56-52219, which mentions is disclosed an inter-region heat supplying system of 2-pipe method also discloses the art which improves the efficiency of individual device and energy efficiency as a whole region.
That is, according to the system, a plurality of heat pump type air conditioning apparatuses distributed over a plurality of places in a region and a power station having central co-generation apparatuses located at a place remote from said places, are connected with a cold water supplying pipe in summer time (the pipe is used as a return pipe in winter time) and a hot water supplying pipe (the pipe is used as a return pipe in summer time).
However, in the system, the two pipes are used for supplying and returning pipe alternately according to seasons by switching water flow by means of three-way valves, and the pipes do not constitute an endless loop as in the system according to the present invention described later. Therefore, a pump is needed for each of the supplying and returning sides, and the larger the amount of power to drive the pumps becomes, the further the distance of the region from the power station becomes.
To solve the problem, Japanese Patent Application Publication No.2000-146356 discloses a regional heating and cooling system in which inter-region piping is formed in a looped endless water passage, not in two going and returning pipes and distributed heat pumps with cryogenic heat accumulator are distributed in a region. That is, the looped endless water passage is of large capacity like a river flowing slowly through a region in order to keep the temperature of the water flowing in the passage as constant as possible.
According to the disclosure, as shown in FIG. 11, an inter-region piping 102 is buried underground to contact directly with the soil without insulation to permit heat-exchange between the water in the piping 102 and the soil, and the water is circulated in the piping 102 by means of a circulation pump 105. Heat pump apparatuses 101a, each having an ice heat accumulator, and heat pump apparatuses 101b without ice heat accumulator distributed over a region are connected with the piping by letting-in-and-out pipes 106. By thermally connecting the circulating water which exchanged heat with the soil to the ice heat accumulator or refrigerant condenser of the heat pump apparatus 101a, the heat the water absorbed from the refrigerant in the condenser or cryogenic heat the water absorbed in the evaporator of each heat pump apparatus is supplied to where they are needed. Preferably, a non-utilized heat sources U are thermally connected to the regional piping 102.
This prior art is different from Japanese Patent Publication No.56-52219 in the point that the regional piping 102 is an looped endless water channel, but the water which exchanged heat with soil is circulated in the regional pipe 102 by a circulation pump 105, so the circulation pump 105 is needed, which is different from the present invention in which does not require a water circulation pump. Furthermore, the capacity of the circulation pump must be increased as the area of the region increases. In other words, as the distance between the ice heat accumulator or refrigerant condenser of the heat pump apparatuses 101a and the place where the heat is used increases. Therefore, the area to be supplied with heat surrounded by the looped endless water channel is restricted.